Manganous chloride (MnCl.sub.2) is useful in dyeing, disinfecting, ceramic coloring, the preparation of alloys, and as an intermediate in the preparation of a variety of other manganese compounds. It is also used to prepare high purity manganese metal by electrolysis of aqueous solutions.
There are numerous commercial methods for the preparation of manganous chloride. Manganese may be directly reacted with chlorine or hydrochloric acid in a hot reactor or aqueous medium. Manganese ore may be reacted directly with hydrogen chloride, treated with ferrous chloride and sulfide, or fused with CaCl.sub.2 /MgCl.sub.2 to produce manganous chloride. Other methods react manganese carbonate or reduced manganese ore with hydrochloric acid.
Many of these methods require the use of high reaction temperatures and specialized equipment to carry out the reaction and to separate the volatile products. Others, conducted in solution, result in the evolution of large volumes of hydrogen gas with its attendant hazards and foaming problems, or incur appreciable manganese loss due to inefficiencies. In the case of aqueous reactions involving chlorine, the manganese is often oxidized to insoluble manganic hydroxide which results in loss of manganese values and poor process efficiency. In addition, if manganous chloride of high purity is the desired product, it is usually necessary to use a relatively pure, and therefore expensive, manganese source.
It would therefore be desirable to provide a process for the preparation of manganous chloride solutions which does not require the use of large amounts of heat energy or special equipment, and which does not suffer from the disadvantage of excessive gas evolution. It would be an additional benefit to provide a process which produces a pure manganous chloride solution from an inexpensive source of manganese.